Abstract:
Antimicrobial activity of co-cultured Lactobacillus fermentum, Saccharomyces cerevisiae
and Pleurotus ostreatus was tested against pathogenic microorganisms isolated from readyto-eat (RTE) foods. Microorganisms were isolated from RTE foods using standard
microbiological techniques. The metabolites from co-cultured L. fermentum, S. cerevisiae and P. ostreatus was tested against isolated microorganisms using agar well diffusion. Bioactive compounds in metabolites was identified using Gas chromatography-Mass Spectrometry (GC-MS). Wistar albino rats were used to evaluate the in vivo antimicrobial efficacy of the metabolites. The bacteria isolated from RTE foods were Salmonella enterica, Shigella dysenteriae, Escherichia coli, Klebsiella pneumoniae (subsp ozaenae), Pseudomonas fluorescens, Bacillus cereus, Listeria monocytogens, and Staphylococcus aureus, while fungiisolated were Penicillium chrysogenum, Aspergillus flavus and Aspergillus niger. The metabolites from co-culture of P. ostreatus + S. cerevisiae and L. fermentum + P. ostreatus + S. cerevisiae showed the highest zones of inhibition of 23.00 mm and 22.00 mm against E. coli and S. aureus respectively and against Aspergillus niger and Penicillium chrysogenum at 20.00 mm and 18.70 mm respectively. Haematological parameters indicated a reduction in the WBC values (34.20×109 g/l, 35.30×109 g/l) and an increase in the PCV (35%, 36%), RBC (17.40×1012 g/l,17.40×1012 g/l) and HB (16 g/l, 16 g/l) of the infected albino rats treated with the co-cultured of P. ostreatus + S. cerevisiae and L. fermentum + P. ostreatus + S. cerevisiae respectively compared with the albino rats infected and not treated which had a WBC value (38.10×109 g/l), PCV (30%), RBC (12.90×1012 g/l) and HB (12 g/l). The histological study revealed that E. coli induced severe damage in the organs of the untreated albino rats, with observable improvements in the organs of the rats treated with the metabolites. The most abundant bioactive compounds in metabolites from co-culture of P. ostreatus + S. cerevisiae and L. fermentum + P. ostreatus + S. cerevisiae were alpha-linolenic acid (ALA), Acetic acid, 3-methylbutyl ester respectively. The pronounced antimicrobial activity against tested microorganisms could be attributed to bioactive compounds in secondary metabolites produced by the co-cultured microorganisms. The metabolites produced by microorganisms can be exploited for production of biopharmaceuticals towards better health delivery system.
